Chlorine (Cl)

About Chlorine

Chlorine is a chemical element with the symbol Cl and atomic number 17, meaning every atom has 17 protons in its nucleus. It is classed as Halogen and is a gas at room temperature. Its atomic mass is about 35.45 atomic mass units (u).

On the periodic table, Chlorine sits in group 17, period 3, which determines how many electron shells it has and how it tends to react with other elements.

Uses of Chlorine

In daily life and industry, Chlorine is used for Bleach, pool disinfectant. These uses are closely tied to the typical properties of elements in the Halogen category.

Electron Structure of Chlorine

Using a simplified electron shell model (at most 2 electrons in the first shell, 8 in the second, 18 in the third, and so on), Chlorine has 3 electron shells, with an approximate arrangement of 2, 8, 7 electrons from the innermost shell to the outermost. This is a simplified learning model, not the full electron configuration that accounts for the s, p, d and f subshells.

Explore Other Elements

Want to see another element or try the element symbol quiz? Go back to the Interactive Periodic Table to explore all 118 chemical elements.

Frequently Asked Questions